INTRO
In this section, we will listen to seismic data at the 3 stations shown in the map below. They represent close, intermediate, and far distances from the earthquake epicenter.
The Background Noise
Before we listen to the earthquakes, we will first listen to the background noise levels at one of the three stations, P39A, in Salisbury, MO.
- What do you notice about the background noise? Are there any dominant frequencies?
Listening to a M9.1 Earthquake
- How do the sounds change as you get farther away from the earthquake epicenter?
- The low frequency waves arriving several hours later – what are they?
Now we will listen to a smaller magnitude (but still quite large!) M7.3 foreshock that occurred a few days prior to the M9.1 on the same fault. This earthquake produced about 1,000 times less seismic energy than the M9.1.
- Can you hear any differences from the larger M9.1? Frequency content? Background noise levels?
Ground Motions for Hait and Tohoku Eqs. from seismicsoundlab on Vimeo.